Electric secondary clock



De. 14, 1943. R. M. WILCOX 2,336,519

ELECTRIC' SECONDARY CLOCK Filed May 13, 1940 FIG. 5 ,7 IHVCHTOI I 25 325+ 15 4 1 5 25 37 1 4 Y Mfi COX B FIG. 3 .FIG. 4 "f? Patented Dec. 14,1943 UNITED STATES PA'IEIlT OFFICE ELECTRIC SECONDARY CLOCK Roy M.Wilcox, Toronto, Ontario, Canada Application May 13, 1946, Serial No.334,683

4 Claims.

This invention relates to electric clock systems in which a master clockoperates a number of secondary clocks by transmitting timed impulsesfrom a source of electric current. Heretofore, clue to the sensitivenessof the secondary clock mechanism, it has not been possible to usealternating current, as the latter sets up vibrations which seriouslyinterfere with the regular and steady operation of the secondary clocks,and makes them noisy in operation. It has therefore been necessary toemploy direct current to avoid thee vibrations and noise.

The object of my invention is to devise an improved, quietly operating,secondary clock mechanism of a type which may be operated by ordinarycommercial alternating current and in which any vibrations are limitedso that they do not interfere with the operation of the clock mechanism.

I attain my object by providing suitable operating means for thesecondary clock mechanism, such, for example, as a pawl and ratchetWheel mechanism, which operating means is in turn actuated by anelectro-magnet of the plunger and solenoid type. This electromagnetincludes an air-tight cylinder in which the armature reciprocates, saidcylinder tending to slow up the inherent quick action of the armaturedue to the use of alternating current. I also provide resilient meansfor frictionally engaging the side of the ratchet wheel to steady thelatter and thus prevent the coasting of the minute hand either forwardsor backwards.

The improved mechanism is hereinafter more specifically described andillustrated in the accompanying drawing in which Fig. l is a top view ofthe clock mechanism;

Fig. 2 a front view of the clock mechanism with the front plate removed,the solenoid and lower end of the armature being shown in section;

Figs. 3 and 4 detail views (looking from below) showing alternativeforms of the connection between the armature and ratchet pawl; and

Fig. 5 a detail of the soldering contact for conmeeting the lead wiresto the solenoid winding.

In the drawing like characters of reference indicate corresponding partsin the different figures.

A supporting frame is provided for the various parts and comprises afront plate 24 and a rear plate 25 connected together by spacer posts4t, 69 and 49 Journalled in suitable bearings in the front and rearplates is a shaft I8, on which shaft is mounted the tubular shaft 2 I.The minute hand I8 is mounted on the shaft l8, while the hour hand 2!shaft 2|.

The tubular shaft 21 is driven from the shaft 18 by means of thefollowing speed reducing gearing. On the shaft [8 is a pinion is whichengages a gear 23 on a short shaft. On this short shaft is a pinion 20which engages a gear 22 on the tubular shaft 2|.

The minute shaft 18 has mounted thereon a ratchet gear IT by means ofwhich it is driven. This ratchet gear is actuated by means of a pawl I5having a hardened point I 5 engaging the gear teeth. This pawl i5 ispivotally connected at 112 with and is actuated by a lever 9 which ismounted on a shaft I 3 rotating in holes in the front and back plates2524. The pin [2, it will be noted, is positioned close to the shaft i3,and is supported by the lever 9 and a disc I 4, Which are both attachedto the shaft 13. The pawl i5 is held against the ratchet gear by theweight of the pawl arm I5. Counterclockwise rotation of the pawl islimited by a pawl shoulder 15 coming against the shaft l3.

This lever 9 is in turn actuated by means of an electromagnet of theplunger and solenoid type. This electromagnet comprises a coil 2, whichreceives impulses from a master clock (not shown), 5 and 5 being theterminals to which the leads from the master clock are connected. Thiscoil is mounted between supports 6 and 6 of insulating materialsupported between the front and rear plates 24 and 25. Within the coil 2is positioned a cylinder I of non-magnetic material insulated from thecoil 2 by a tube 3. In this cylinder reciprccates the piston armature 4,the outer end of which armature is connected to the lever 9 by a pin land slot 39 connection. The piston armature 4 is a sufficiently closefit in the cylinder i so that when the armature is attracted into thecoil, the air trapped in the cylinder I leaks out gradually thus slowingthe armature on its inward travel. If the armature were not slowed downby said air trap, the armature would give the ratchet wheel and minutehand enough momentum to coast one or more extra teeth, thus putting thesecondary clock out of step with the master clock. The said air trapalso helps to dampen vibration of the armature 4.

The closed end of the cylinder l extends somewhat beyond the coil andits magnetic field, with the result that when the coil is energized andthe armature is attracted into the coil, its momentum is checkeddirectly by the air entrapped in the closed end of the cylinder and theinner end of the armature is spaced from the closed is mounted on thetubular end of the cylinder as indicated in dotted lines at 1 thusavoiding hammering or chattering of the piston armature against thecylinder end due to the vibrating magnetic pull of the coil 2.

A steel field piece II is mounted on the cylinder l at a pointintermediate the end support 6 and closed end of said cylinder I. Thissteel field piece H concentrates the magnetic field of the coil 2 sothat the armature receives an almost steady pull up to the dotted line 4which indicates the practical limit of the magnetic field, consequentlythere is no magnetic pull beyond said line to cause the armature to movefurther inward after being checked by the air compression and theconcentrated magnetic influence of the field piece it tends to hold thearmature to the inward limit of movement, thus obviating a bouncingeffect on the armature and ensuring a definite operating movement of thedriving pawl.

A friction washer 26 and spring washer 21 are interposed between theratchet wheel ii and the rear plate, which washers exert a frictionalsteadying effect on the ratchet wheel to prevent the minute handcoasting because of unbalance or momentum and to prevent the ratchetwheel being pulled back by the pawl l5. This type of steadying meansdoes not cause vibration of the armature 4, and does not wear the teethof the ratchet wheel 11.

A stop rod 8 is mounted between the front and rear plates to limit thedownward movement of the piston 3, and thus regulating the length of itsstroke.

It will be evident, of course, that an ordinary pivot connection may besubstituted for the pin and slot connection I in which case the solenoidas a whole may be pivotally mounted.

In Fig. 3 a modified arrangement of mounting the lever t and ratchetpawl I5 is shown. In this arrangement, a shaft 33 is carriedbyeccentrics Ed and 3 1 said shaft and eccentrics forming a part of thelever 9 The ratchet pawl i5 is pivoted on the shaft 36. I

A further modification is shown in Fig. i. The lever 2 is mounted on ashaft 3': having eccentrio pivots in the plates 2d and 25 and theratchet pawl is mounted on the shaft 31.

In Figs. 5 and 1 is shown a method of securing the soldering contacts 5and 5" in place. This small, shee isinserted through holes in the endpiece 6 or 6. The ends of the contact are bent over and im bedded in theback of the coil end 8 so that they do not project and interfere withthe winding of coil 2.

In operation, an impulse from the master clock energizes the coil 2,whose magnetism draws the armature 1i upward, thus rocking the lever andpushing the pawl i5 upwardly to rotate the -metal contact formed in aU-shape,

ratchet wheel 11. When the said impulse is ended, the armature dropsdownward under its own weight and the pawl point it drops into positionto engage the next tooth of the ratchet Wheel.

What I claim as my invention is:

1. In an electric secondary clock, the combination with the actuatingshaft of the time indicators, of ratchet means for rotating said shaft,a solenoid type electro-magnet Wound for an alternating current andhaving a tubular core extending above the magnetic field and closed atits upper end, and a piston armature operating in said tubular core andoperatively connected with said ratchet means and cushioned at the upperend of its power stroke within said tubular core to offset the vibratoryinfluence of the alternating current thereon during the period of flowof current through said solenoid.

2. In an electric secondary clock, the combination with the actuatingshaft of the time indicators, of a solenoid type electro-rnagnet woundfor alternating current and having an axial orifice therethrough, acylinder of non-magnetic material arranged within said axial orificehaving a closed end extending beyond its magnetic field, a pistonarmature operating in said cylinder and cushioned by the air entrappedin the closed end of saidcylinder, and means operatively connected withsaid armature adapted to impart rotary movement to said actuating shaft.

3. In an electric secondary clock, the combination with the actuatingshaft of the time indicators, of a solenoid type electro-magnet woundfor alternating current having an axial orifice therethrough, a cylinderof non-magnetic material arranged within the axial orifice of saidmagnet and having a sealed end extending beyond the magnetic field, apiston armature operating in said cylinder, means connected with saidarmature for imparting rotary movement to said actuating shaft, and amagnetic field piece surrounding said cylinder between the solenoid andthe sealed extremity thereof.

4. In an electric secondary clock, the combination with the actuatingshaft of the time indicators, of a solenoid type electro-inagnet woundfor alternating current, a piston armature reciprocable in said magnet,alever supported at one end on a fixed pivot and pivotally connected'atthe other end to said piston armature, a ratchet wheel mounted on saidactuating shaft, a pawl pivotally mounted on said lever closely adjacentto the fixed pivot support thereof said pawl engaging said ratchet wheelto impart turning movement to said shaft, and means Within said solenoidfor offsetting the vibratory influence of the alternating current.

ROY M. WILCOX.

